Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1999
Randomized Controlled Trial Clinical TrialRecovery characteristics of sevoflurane and halothane in preschool-aged children undergoing bilateral myringotomy and pressure equalization tube insertion.
This double-blinded study was undertaken to prospectively evaluate the role of halothane and sevoflurane and the use of IV ketorolac on the anesthetic emergence in a group of children undergoing bilateral myringotomy with pressure equalization tube procedures. Two-hundred ASA physical status I and II patients were premedicated with nasal midazolam (0.2 mg/kg) and randomized to one of four groups (Group 1 - halothane and ketorolac; Group 2 - halothane and placebo; Group 3 - sevoflurane and ketorolac; Group 4 - sevoflurane and placebo). A blinded nurse observer characterized the quality of the anesthetic emergence and recorded the incidence of emesis and the use of pain medications in the recovery room. There were no differences in age, weight, previous anesthetic experience, or duration of anesthesia among the four groups. There was no difference in the incidence of emergence agitation for patients anesthetized with sevoflurane compared with halothane, regardless of whether they received ketorolac or placebo. Regardless of the anesthetic, the incidence of emergence agitation was significantly less in patients who received ketorolac compared with patients who received placebo. The incidence of emesis in the recovery room, the total 24-h incidence of emesis, and the use of at-home pain medications were similar in all four groups. ⋯ We conclude that the incidence of emergence agitation in children undergoing ultrashort anesthetic procedures is similar for sevoflurane and halothane and that ketorolac markedly diminishes emergence agitation and/or pain behavior.
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Anesthesia and analgesia · Jan 1999
Anesthesia for cesarean section and acid aspiration prophylaxis: a German survey.
We surveyed routine anesthetic practice and measures to prevent acid aspiration syndrome (AAS) in patients undergoing cesarean section (CS) throughout Germany. Of 1061 questionnaires, 81.9% were returned. For scheduled CS, general anesthesia was used in 63% of cases, and for urgent CS, it was used in 82% of cases. Regional anesthesia was used less often for both scheduled and urgent CS in smaller (< or =500 deliveries/yr; 28% and 16%, respectively) than in medium-sized (500-1000 deliveries/yr; 42% and 19%, respectively) or major obstetric departments (>1000 deliveries/yr; 45% and 21%, respectively). Among the regional techniques, epidural anesthesia (59%) was preferred more than spinal anesthesia (40%) in scheduled CS. In urgent CS, spinal anesthesia predominated (56% vs 42%). Pharmacological AAS prophylaxis is routinely used in 69% (68%) of departments before elective (urgent) CS under general anesthesia and in 52% under regional anesthesia. H2-blocking drugs are preferred for AAS prophylaxis over H2-blocker plus sodium citrate and sodium citrate alone. Both the incidence of and the mortality from AAS at CS are very low in Germany (<1 fatality per year). Nevertheless, AAS prophylaxis deserves more widespread use in obstetric anesthesia and in other patients at risk (e.g., children, outpatients). ⋯ According to a countrywide survey, the use of regional anesthesia for cesarean section and pharmacological prophylaxis of acid aspiration syndrome is considerably less common in Germany than in the United States, United Kingdom, or other European countries.
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Anesthesia and analgesia · Jan 1999
Clinical TrialA new approach for brachial plexus block under fluoroscopic guidance.
We performed the subclavian perivascular approach to the brachial plexus using contrast medium to confirm the location of the tip of the needle and the spread of the injected solution to obtain a high success rate and to minimize the risk of pneumothorax. Review of the cases led to the hypothesis that the solution injected inside the costal attachment of the middle scalene muscle spreads into the interscalene space. Because of the difference in the placement of the tip of the needle using our technique and the supraclavicular approach, including the subclavian perivascular approach, we termed our technique the supracostal approach. We conducted the present study to establish the supracostal approach by proving this hypothesis. A total of 173 blocks in 149 adult patients were studied. Eighty-four blocks in 74 patients were achieved by using the supracostal approach with contrast medium. The needle was inserted 1 cm lateral to the palpated subclavian artery and 1-2 cm above to the clavicle to touch a specific part of the first rib, which we believed to correspond to the inside of the costal attachment of the middle scalene muscle. After injecting the anesthetic solution with contrast medium, radiographs were obtained for each block, while computed tomographic (CT) studies were performed for five blocks. Five blocks in five patients were achieved by using the subclavian perivascular approach with contrast medium and both radiographs and CT studies. In addition, the anatomical difference between the two approaches was evaluated in five adult cadavers. Based on these studies, we determined the proper part of the first rib that corresponded to the inside of the costal attachment of the middle scalene muscle. Eighty-four blocks in the remaining 70 patients were performed with the supracostal approach without contrast medium. Of the 84 blocks with contrast medium, 80 (95%) produced successful blockade defined by sensory and motor examination. The radiological studies showed that, with the supracostal approach, the injected solution, which spread from the middle scalene muscle into the interscalene space, did not spread below the first rib. However, with the subclavian perivascular approach, the solution was confined within the perineural sheath and spread below the first rib to the axilla. The anatomical studies could explain this difference, revealing that the perineural space of the brachial plexus is not identical to the interscalene space. There was no failure in the 84 blocks performed with the supracostal approach without contrast medium after we determined the proper part of the first rib. We conclude that the supracostal approach to the brachial plexus is reliable, easy to perform, and associated with a low complication rate. ⋯ A new fluoroscopically guided approach for brachial plexus block has been established on the basis of anatomical and radiological studies to be reliable, easy to perform, and associated with a low complication rate.
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Anesthesia and analgesia · Jan 1999
The growth of microorganisms in propofol and mixtures of propofol and lidocaine.
Propofol emulsion supports bacterial growth. Extrinsic contamination of propofol has been implicated as an etiological event in postsurgical infections. When added to propofol, local anesthetics (e.g., lidocaine) alleviate the pain associated with injecting it. Because local anesthetics have antimicrobial activity, we determined whether lidocaine would inhibit microbial growth by comparing the growth of four microorganisms in propofol and in mixtures of propofol and lidocaine. Known quanta of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans were inoculated into solutions of 1% propofol, 0.2% lidocaine in propofol, 0.5% lidocaine in propofol, 0.5% lidocaine in isotonic sodium chloride solution, and 0.9% isotonic sodium chloride solution. All microorganisms were taken from stock cultures and incubated for 24 h. Growth of microorganisms in each solution was compared by counting the number of colony-forming units grown from a subculture of the solution at 0, 3, 6, 12 and 24 h. Propofol supported the growth of E. coli and C. albicans. Propofol maintained static levels of S. aureus and was bactericidal toward P. aeruginosa. The addition of 0.2% and 0.5% lidocaine to propofol failed to prevent the growth of the studied microorganisms. The effect of 0.5% lidocaine in isotonic sodium chloride solution did not differ from the effects of isotonic sodium chloride solution alone. We conclude that lidocaine, when added to propofol in clinically acceptable concentrations, does not exhibit antimicrobial properties. ⋯ Local anesthetics such as lidocaine have antimicrobial activity. Propofol supports the growth of bacteria responsible for infection. Bacteria were added to propofol and propofol mixed with lidocaine. The addition of lidocaine to propofol in clinically relevant concentrations did not prevent the growth of bacteria. The addition of lidocaine to propofol cannot prevent infection from contaminated propofol.
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Anesthesia and analgesia · Jan 1999
Randomized Controlled Trial Clinical TrialThe safety and effectiveness of remifentanil as an adjunct sedative for regional anesthesia.
We assessed the sedative potential of continuous infusions of remifentanil with a validated composite alertness scale in 160 patients (ASA physical status I or II) undergoing hip replacement surgery with spinal block (n = 61) or hand surgery using brachial plexus block (n = 93). They were randomized to receive one of the following initial dose regimens in double-blinded fashion: placebo or 0.04, 0.07, or 0.1 microg x kg(-1) x min(-1) remifentanil subsequently titrated to effect. Additional midazolam IV was allowed for adequate sedation as required. The combined analysis of both surgery groups revealed a dose-related increase in achievement of sedation level > or =2 within 15 min of the start of the study drug infusion; all remifentanil dose comparisons with placebo reached significance (P < 0.001). The remifentanil 50% effective dose for a composite sedation level > or =2 within 15 min of the start of drug infusion was estimated as 0.043 microg x kg(-1) x min(-1) (95% confidence interval 0.01, 0.059). The requirement for midazolam decreased with increasing remifentanil dose compared with placebo (P < 0.001). The median time to return to alertness after the end of infusion was 10-12 min in the remifentanil groups and 5 min in the placebo group. Significant incidences of nausea, pruritus, sweating, and respiratory depression were reported during remifentanil infusions compared with placebo. The data suggest that remifentanil may be useful for supplementation of regional anesthesia, provided that ventilation is carefully monitored. ⋯ In this dose-finding, placebo-controlled study, remifentanil infusions were used to provide sedation during spinal and brachial plexus regional anesthesia. The 50% effective dose for achievement of sedation was 0.043 microg x kg(-1) x min(-1). Return to alertness occurred after 10-12 min (median time). Remifentanil infusions can be used to supplement regional anesthesia, but this requires careful monitoring of ventilation.